1. Field of the Invention
The present invention is directed to a method for the detection of fissile or radioactive material or radiation shielding material. More particularly, it is directed to a method to detect the presence of radioactive or radiation shielding materials in a shipping container where the contents of the container are listed on a manifest, packing slip or other list of contents.
2. Background of the Art
On Sep. 11, 2001, the United States was attacked by a terrorist network named al Qaeda. The al Qaeda terrorists hijacked four commercial airliners to launch a massive attack. The terrorists flew a hijacked airliner into each of the two towers of the World Trade Center in New York City and one into the Pentagon in Washington, D.C., the military headquarters of our country. The efforts of courageous airline passengers and crew foiled the attempt to fly the fourth hijacked airliner into an additional target, most likely in the Washington, D.C. area, by causing it to crash into the Pennsylvania countryside. In all, over 3,000 people were killed on American soil on the morning of Sep. 11, 2001.
The September 11 attacks were a wake-up call for America. Americans suddenly realized that our free and open society was vulnerable to terrorist attack in many ways. Everywhere, Americans saw vulnerabilities, especially to “weapons of mass destruction” such as nuclear weapons. One type of nuclear weapon is a device, such as a bomb or warhead, whose great explosive power derives from the release of nuclear energy.
Another type of nuclear weapons includes the so-called “dirty bomb.” A dirty bomb is a conventional explosive device packed with radioactive material to spread radioactive contamination that causes sickness in human beings. Radiation sickness is illness induced by exposure to ionizing radiation, ranging in severity from nausea, vomiting, headache, and diarrhea to loss of hair and teeth, reduction in red and white blood cell counts, extensive hemorrhaging, sterility and death.
Vulnerability of harm to the populace caused by terrorists from nuclear weapons requires that such weapons be delivered to and detonated in the target area. However, a terrorist relies on stealth in which to deliver a weapon and not conventional military means of delivery. For example, a terrorist may be able to stealthily deliver a nuclear weapon onto American soil by secreting it in one of the tens of thousands of shipping containers that are brought into the United States every day.
One of the purposes of this invention, when used together with radiation detection and radiation shielding detection devices, is to prevent the transportation of nuclear weapons by stealth in shipping containers into and out of ports anywhere in the world, in general, and into and out of ports in the United States, in particular. A further purpose of this invention, when used together with radiation detection and radiation shielding detection devices, is to prevent nuclear weapons from being imported into the United States by stealth in shipping containers that are (1) loaded in foreign ports; (2) transported to the United States by ships, including huge ocean-going containerships that carry upwards of 4,000 twenty-foot-equivalent units (“TEUs”) shipping containers; and, (3) unloaded in, or brought into close proximity to, ports or population centers in the United States. Using this invention together with radiation detection and radiation shielding detection devices, the threat from terrorists attacking the United States or any other nation with nuclear weapons brought into proximity to population centers by stealth in a shipping container can be mitigated.
a. Detection Systems
It is known in the art of nuclear weapon detection technology that uranium based nuclear weapons emit detectable gamma rays. Given the periodic table symbol “U,” uranium is a heavy silvery-white metallic element, radioactive and toxic, easily oxidized, and having 14 known isotopes of which U 238 is the most abundant in nature. The element occurs in several minerals, including uraninite and carnotite, from which it is extracted and processed for use. It has an atomic number 92; atomic weight 238.03; melting point 1,132° C.; boiling point 3,818° C.; specific gravity 18.95; valence 2, 3, 4, 5, 6. Uranium is enriched in a process whereby the amount of one or more radioactive isotopes in the material is increased.
It is also known in the art of nuclear weapon detection technology that plutonium based nuclear weapons emit detectable gamma rays. Given the periodic table symbol “Pu,” plutonium is a naturally radioactive, silvery, metallic transuranic element, occurring in uranium ores and produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu 244 with a half-life of 76 million years. It is a radiological poison, specifically absorbed by bone marrow, and is used, especially the highly fissionable isotope Pu 239, as a reactor fuel and in nuclear weapons. It has an atomic number 94; melting point 640° C.; boiling point 3,235° C.; specific gravity 19.84; valence 3, 4, 5, 6.
Since the 1911 work of Hans Geiger, it has been know that devices can detect the presence of ionizing radiation. Named the Geiger-Müller counter, an improved version of the device detects alpha particles, electrons and ionizing electromagnetic photons. Modernly, plastic scintillation is used to detect gamma radiation. For example, Canberra Industries, Inc. of Meriden, Conn. (www.canberra.com) manufactures and markets monitors that use scintillation detectors designed for the radiological control of pedestrian vehicles, trucks and rail cars. For another example, Amptek, Inc. of Bedford, Mass. (www.amptek.com) manufactures and markets a “Gamma-8000” scintillation detector that utilizes sodium iodide crystal detection and digitalization to detect and spectrographically analyze gamma radiation. There are other devices commercially available that can be used to detect radiation, including those that use both scintillating and non-scintillating materials (solid state detectors such as mercuric iodide or cadmium telluride). In this description and the appended claims, all of these devices are generically referred to as “‘fissile or ’ radioactive material detection device(s).”
It is known in the art of nuclear weapon detection technology that the presence of uranium or plutonium based nuclear weapons can be concealed by covering the weapon with radiation shielding material such as lead. Given the periodic table symbol “Pb,” lead is a soft, malleable, ductile, bluish-white, dense metallic element, extracted chiefly from galena and used in containers and pipes for corrosives, solder and type metal, bullets, radiation shielding, paints, and antiknock compounds. It has an atomic number 82; atomic weight 207.2; melting point 327.5° C.; boiling point 1,744° C.; specific gravity 11.35; valence 2, 4. A nuclear weapon could be placed in a shipping container and then covered with a layer of radiation shielding material, typically lead of one to two inches or more in thickness. In this way, the fissile or radioactive material detection device or devices may not be capable of identifying the presence of the nuclear weapon. Thus, radiation shielding material can be used to deliver and detonate a nuclear weapon on American soil by bringing the weapon into the country by stealth in a shipping container.
Other shielding materials are also known in the art. For example, high density concrete is typically used to contain radioactive emission in structures. The thickness of high density concrete to shield a nuclear weapon placed in a shipping container could be in the same order of magnitude as the thickness of lead required in the above example. All of these shielding materials will attenuate or entirely block gamma radiation such that the presence of fissile or radioactive material cannot be detected.
There are two major limitations on the use by terrorists of radiation shielding material to shield the radiation emanating from a nuclear device hidden in a shipping container: (1) an x-ray or other similar detection system can detect the presence of an amount of radiation shielding material necessary to shield the radiation emanating from the nuclear device; and, (2) the maximum amount of weight of the shipping container permitted by various state and federal regulations in the United States in order that the container be truly intermodal (the so-called “over-the-road” weight limitation). In either event, as more fully discussed below, the presence of the concealed weapon has been indirectly made known through the presence of the shielding material, thereby thwarting the terrorist attack.
First, x-ray or other similar detection inspection systems of shipping containers to attempt to discern the presence of radiation shielding material are well known in the art. For example, some of these inspection systems typically produce a transmission image by the measurement of the intensity distribution of the x-rays that transverse the shipping container. X-ray or other such detection systems rely on a source that emits x-rays, gamma rays or other radiation. These are sometimes referred to as “active” systems in the sense that they generate radiation to be passed through an object to be scanned, and then measure the intensity, location or other attribute of the radiation exiting such object. Thus, radiation shielding material used to cover a nuclear weapon can be detected by the use of such x-ray or other active detection systems, since such material would be absorptive of the radiation.
However, the use of active detection systems to detect radiation shielding suffers from serious drawbacks. Active detection systems (1) produce harmful radiation and thus are not suitable for the work environment; (2) can damage certain types of cargo carried in containers such as photographic film; (3) require a separation space between the radiation source and the detector into which space the inspected container must be placed; and, (4) are difficult to accommodate on the hoist attachment of the container crane.
The present invention permits the effective use of a passive system of detection. It is used together with radiation detection devices that merely record the presence of gamma rays. The system is passive in the sense that it only relies on the spontaneous radiation emitted by fissile or radioactive material, a radiation detector, a computer, a list of the contents said to be in the container (the “manifest”) and software product. In this description and the appended claims, all of these systems and devices, active and passive, will be referred to as “radiation shielding detection device(s).”
b. Shipping Container Systems Or Containerization
Since the late 1960's, the use of shipping containers for ocean-going transportation or containerization has been prevalent. The shipping container has significant advantages over the old, so-called “break bulk” system of lashing and shoring of cargo in the cargo holds of “tween deck” vessels or any other type of break bulk system, e.g., LASH barges. Containerization makes intermodal transportation a reality. Once cargo is loaded into a container at its origin (usually by its manufacturer or seller), containerization makes possible the transportation of the container by truck, rail and ship, over land and sea, to its destination without disturbing its contents. Containerization creates greater speed of transportation while, at the same time, less expensive handling, damage and theft.
As with all ocean going freight systems, in containerization, the port or ports of loading and unloading (embarkation and disembarkation) constitute major bottlenecks. At the load port, the full container is taken into the container yard. There, the container's identification (the “Container ID”) is recorded for many purposes, including tracking and location purposes. The Container ID can be alphanumeric, numeric, a bar code or other identification designation. At or before this time, the contents in the container are recorded for inclusion on a list or manifest. The manifest lists each container and the contents of each container with specificity (the “ship's manifest”). Transportation companies often create databases that contain the manifest information associated with each container (a “manifest database”). Among other things, the manifest database contains a commodity identification designed to represent the contents in each container (the “Commodity ID”). Commodity IDs have been standardized by the U.S. International Trade Commission (the “standardized Commodity ID”) and are sometimes referred to as “harmonized tariff code numbers” or “HTC numbers.” (See, Harmonized Tariff Schedule at http://dataweb.usitc.gov/SCRIPTS/tariff/toc.html).
At the load port, the full container is stored, usually in an open yard, to await loading aboard the containership. During this period of storage, the full container can be inspected. However, inspection in the container yard requires that an additional step or function take place, namely, additional handling by additional personnel.
Similarly, at the load port, the partially loaded container is taken into the container yard. There, the Container ID is recorded for many purposes, including tracking and location purposes. Prior to storage in the container yard, the cargo in the partially loaded container may be consolidated with other cargo either in the same container or in another container. At or before this time, the container and its contents are listed on the manifest and in the manifest database. Thereafter, the container is stored in the container yard to await loading aboard the containership. During this period of storage, the container can be inspected. However, once again, inspection in the container yard requires that an additional step or function take place, namely, additional handling by additional personnel.
Tens of thousands of containers are loaded and unloaded in the ports of the world every day. However, only a very small percentage of these containers is inspected. For example, anecdotal evidence suggests that of the some 21,000 containers unloaded in the ports of the United States every day, less than 3% are inspected. This situation represents a major vulnerability to terrorism and other unlawful conduct due to the possibility of concealment of nuclear weapons. Accordingly, a need exists in the art to mitigate the possibility of an attack on the United States, or any other nation or population, with nuclear weapons brought into proximity to population centers by stealth in a shipping container.